Telephone-exchange system



F. A. STEARN TELEPHONE EXCHANGE SYSTEM June 9, 1925.

'7 Sheets-Sheet l Filed Apl 11 1921 June 9, 1925.

F. A. STEARN TELEPHONE EXCHANGE SYSTEM Filed April 11. 1921 7 Sheets-Sheet 2 June 9, 1925, 1,541,468

F. A. sTEARN TELEPHONE EXCHANGE SYSTEM Filed Api'l 11. 1921 .7 Sheets-Sheet 3 l gua-lf.

June 9, 1925. 4 1,541,408

FY A. STEARN TELEPHONE EXCHANGE SYSTEM Filed April 11, 1,921 7 sheets-sheet v4 June 9, 1925.

F. A. STEARN TELEPHONE EXCHANGE SYSTEM 'Filed r11 11, 1921 'TSheets-Sheet #Wen/0r.' FMW/f//h A. Semf/z V RWM /l/fjy.

June 9, 1925.

v F. A. STEARN TELEPHONE EXCHANGE SYSTEM Filed April 11.\ 1921 7 Sheets-Sheet 6 June 9, 1925.

F. A. STE-RN TELEPHONE EXCHANGE SYSTEM April 11, 1921,` 7 Sheets-Sheet 7 vt@ bf@ Patented .lune 9, 19.25.

nire stares FRANKLIN A. STEABN, 0F PATEESGN, COMPANY, TGQEFQRATED, OF NEVI NEW JERSEY, ASSIGNQR ro WESTERN ELECTRIC YORK, N. Y., A. COEPQBfrTVON OF NEW YORK,

TELEPHONE-EXCHANGE SYSTEM.

Application filed. April 11, 1921. Serial No. YL605:118.

To au who/:vi t may concern:

Be it known that l, FRANKLIN S'uiAiiN, a citizen ot the United States ot America, residing' at aterson, in the county of Passaic, State oit New Jersey, have invented certain new and useful improvements in Telephone-EXchange Systems, ot which the tollowing is a itull, clear, concise, and exact description. I l

rlhis invention relates to telephone exchange systems and iiarticularly to systems wherein talking connections between subscribers lines are Vestablished in part by means of machine switching apparatus and in part by the use ot' equipment manipulated by central ottice operators.

In certain semi-automatic systems the subscribers lines are terminated in jacks at operators positions in the central ottice. So tar as-thc subscriber is concerned his line is identical in all respects to an ordinary inanual line. To make a call he removes his receiver from its switch hook Cates the wanted number to the responding loperator. it the central otiice, too, the duties of the operator correspond in come respects to those ot the usual manual operator. She answers the calling line by inserting the plug ot an idle cord circuit at her position in the ack ot the calling line. On receiving the number ot the desired line from the calling party she'then proceeds to record the same on a set of keys, which determine the operation ot a register 'controlling mechanism to govern the selective operation of automatic switchesv in the extension of the call. In order that the operator may be relieved ot the manipulation oi listening keys, each time a call is answered, for connecting` her telephone set to the callirg` line and disconnecting it therefrom certain instrumentalities are used to accomplish tht` same automatically.

rllhe object ot the present invention is the provision, in a system ot the above described character, ot an arrangement consisting` ot a combination ot relays, the function ot which to instantaneously connect the operators head-set to and disconnect lthe same 'from the connecting circuits at lier position and which also serves under certain conditions to prepare for the disassociation of the register sender from the particular Vcircuit v1ith which it may be associated at the time.

and communi- A feature of the invention relates to the provision ot connecting relays, one for each ot the cord circuitsy at an operators 'position, the relay oi a particular cord being operative when the cord is taken for use to connect the operators telephone set thereto and means, when a second cord is taken tor use, for shunting out the relay of the first cord and permitting the connecting relay of said second cord to operate to transfer the operators set from the lirst to the second cord circuit.

Another 'feature of the invention relates to .means operated simultaneously with the operation ofthe connecting relays in the transfer of the operators set from the lirst to the second cord Circuit, while a register sender is attached to 'such iirst cord, forsetting up a condition in advance which subsequently causes the sender to be disasseciated from the first cord after said sender has completed its switch-controlling Jfunctions. 'y

vA still further feature has to do with the provision ot a marginal relay, which Operates whenv included in a circuit extending through more than one of the connecting relays individual to the cords, during the transfer of operators set fromone cord to another, and which marginal relay in operating sets up in advance a condition for later causing tlierelease ot the register sender when saidsender has completed its switch controlling functions.

Such otherand further features as are contemplated in the present invention will become more fully understood `from a consideration of the :tollowing detailed descrip,

tion and the appended claims. l

In the drawing Figs. l to 7 inclusive,

Vwhen the corresponding sheets are arranged in the order pictured in Fig.v 8, disclose a telephone exchange system embodying the subject mattei' ot'- the invention. Fig. 1 shows an operators position at which incoming subscribers lines terminate in answering jacks, one such line being illustrated.` @ne of a plurality ot' cord circuits is also shown in this figurer by means of which the operator responds to calling lines, each ot such cord circuits terminating in the brushes ot a district selector switch.

FigrQ illustrates the operator-s telephone set and the necessary ,equipment whereby subscribers said set is connected to and disconnected from the cord circuits at her position in response to certain acts on the part ot the operator, and also automatically in response to certain conditions brought about in the progress of establishing connections.

Fig, 3 shows one ot a plurality of cord finder switches for attaching the associated register sender with the cords at the operators position, together with an allotter switch for allotting an idle cord finder sender and register sender unit ior use.

Fig. 4 shows partially the otiiee keys on theoperators keyboard together with the oiiice registers of a register sender, to a plurality of which senders said keys are common. f

Fig. 5 shows a portion of the four rows of numeral keys on the operators keyboard and the corresponding numerical registers of the same register sender.

G illustrates a set of countine' relays and theI sender sequence switch which cooperate to control the setting ot' the selective switches in accordance with the'desig nations represented on theA registers.

7 shows an o'fiice selector' switch to which calling lines are extended by way of the district selec-tor shown in Fig. l. This gure also illustrates, by the schematic showing of the brushes, an incoming and a final switch which participate in the establishment oi a complete connection through to the called subscribers lines, one of which is shown.

A.' hereinbefore n'ientioned the calling lines terminate in jacks at answering operators positions. The operatoris provided with a plurality ot cord circuits one end oi' which terminates in an answering plug and the other in the brushes of a district selector switch. In responding to a calling line, the indication oit which is given to her in the usual manner by means ot' a calling lamp, the operator inserts the plug of an idle cord circuit in the jack ol' said line. This act on the part `ot the operator immediately causes her telephone set to be auton'iatically connected to tbe cord circuit taken tor use in order that she may converse with the calling subscriber to ascertain his wants. The connection ot the operators telephone set to the cord circuit is made by means of a quick operating device, such as a relay, and is maintained un til the establishment ot the desired connection has progressed to a certain point, at which time her telephone set is automatically disconnected by the register sender, or until the operator actuates a listening out key in case for any reason she wishes te hasten the. disconnection of ber talking equipment.

Furthermore, the act of inserting the plug of the cord circuit in the jack of the calling line initiates the operation ot an allotted idle cord tinder and register sender unit, such as the one shown in Figs. 3, si, 5 and 6. The cord finder 3&0, which has access to sets of terminals in its bank repre seating all oi the cord circuits at the eperators position, is driven in a'huntin-gl movement to iind the set ot terminals identi- 'tying the particular cord that the operatorV Y has taken for use. The cord finder in tinding the. proper cord circuit associatesthere with the register sender unit upon which the operator records the designation oi' the called line, and which thereafter serves to control the operation ol the selective switches to extend the calling line to the desired otlice and thence to the called line therein. n

The operatoi"s keyboard, which is common to all of the register sender units ot her position, is comprised of two distinct parts. `The iii-st part comprises what may be called the office or tandem keys. In Fig. 4- there is illustrated three rows of such keys, 400, 401 and 402. Vly actuating the ot keys the operator may canse the sett-im;` of the class and otiice registers 401i, 405, 406, y0T and 408 in accordance with the code designations identifying the various oiices in the telephone area to which connections trom the oiiice here illustrated may be ef;- tended, ln other words, that part oit the, total designation which represents the oiiice containing the called line may consist ot three characters, either numerals or letters, and according to the code ot these characters the oiiicc keys, shown in Fig. -l, are adapted lo produce the recordoir the oiiice registers to iu turn control the setting ol2 the district and oliice switches. Figs. l and 7, to extend the connection to the desired ottice. Tivhere the traiiic to certain outlying offices is comparatively hearji' und a la e number ot calls are handled in the co use et a day, it is found .lesirable to pro- .Y a single key ior such oi'iices to take the place oi" the combination of three keys in the rows 400-101 and 402. Such a key is shown at 403 and serves the same purpose in setting up the entire record on the Yotiice registers as would be accomplished by the depression ot a key in each oi the three rows 400, 401 and 402. rl`he second part ot the operators keyboard consists ot Jfour rows of numerical keys 500. 501, 502 and V5l on which the number ot the desired line is recorded to effect the sett-ing ot the numerical registers, 50st, 505, 500Y and 507. rhe stations register 508 is provided and where the called line is one containing a plurality of substations, stations keys may alsobeinstalled at the operatoids.position to determine the selection otr-inging current. In the present disclosure, however,

k ditlierent combinations ol these three rows` the stations keys haife `been omitted and a single start key 520 is used for a purpose hereinafter to be explained. y

rlhe operator having received the name of the oilice and the number of the called line therein from the calling subscriber', now proceeds toset up the code on the ollice keys representing such office andv also to record the numerical designation of the line on the numerical keys. YWith the registers in their corresponding positions the sender next becomes effective to control the setting of the switches to establish the connection.

The district and ofice selector switches shown in full in Figs. 1 and 7, and also the inc-inning selector represented diagrammatically by the brushes 727, T28 and 7 29, and the 'inal selector represented diagrammatically by brushes 733, 734 and 735 may be of the general type and constructionshown in the patent to Craft and Reynolds 1,123,696 issued January 5, 1915.

The cord finder switch illustratedv in Fig. El is also of the same general character except that in this rcase a single set of brushes is mounted on the shaft and driven by the source of power over the terminals of the bank. 1

The sequence switches 110, 710 and B10, which control the circuits of the district selector, oftice selector and cord finder switches, are'of the well known type disclosed in the patent to Reynolds and lBaldwin 1,127,808 issued February 9, 1915. The sender sequence switch 610, the allotter switch B20 and the several registers shown in Figs. et and 5 are also of the same construction. lYhe-re thev cord finder vscouience switch 310 and the allotter scquence'switch 320 both occur on the saine sheet, confusion avoided by locating all contacts controlled b v the latter sequence switch within the area set ofi' by broken lines in the upper right-hand corner. In vFig. l the'A several contacts belonging to the class register' 40d and the oiiice registers405, 406, 407 and 408 are segregated respectively within the spaces set otf by the vertical broken lines. rl`he same plan is used in Fig. 5 with respect t0 the contacts belonging to registers 504, 505, 506, 507 and 508.

With the` foregoing general description of the system in mind, it is believed that a more thorough understanding of the invention may now be had by considering the detailed operation involved in the establishment of a complete connection. For this purpose it will be assumed that a calling` subscriber, such as the subscriber at substation 1007 desires to communicatewith the subscriber of line 7410.

The operator responds t0 a call initiated by av subscriber.

The subscriber at substation 100, onliniand contact of relay 200.

tiating a call, completes a circuit forthe line relay 101 extending over the arinatures and contacts of cut-olii relay 102 and the loop of the line. Relay 101 completes a circuit for the calling line lamp 107, the illumination of which notities the operator that a call is awaiting her attention. The operator thereupon seizes plug 104i of an idle cord circuit at her position and inserts it in the jack 103 of the calling line.. A. circuitis thereby completed from battery through the winding of relay 102, sleeve of jack 103, sleeve of plug 1011, conductor 165, normal con'acts at the right-hand armature ot' relay 208, winding of relay 109 to ground, causing the energization of both relays 102 and 109. Relay 102 opens the circuit of relay 101, which in turn causes the effacement of lamp 107. Relay 109 completes a circuit from subbattery through its right-hand armature and contact, conductor 170, winding of rela 200 to Ground.

lt may be well to note at this point that both main and subbattery are used in this system, the difference being indicated in the drawingvby showing twicetheA number of cells for the main battery as for the subbattery. .'lhe positive pole of the main battery is grounded, whereas the sub-battery has its negative pole grounded. `Wherever, in tracing' circuits7 the subbattery is involved the same will be referred to as such, but in describing circuits which include the main battery no special` mcmtionv will be made thereof. Y

lRelay 200 energizes in the'above traced circuit and closes a circuit from battery through the winding of marginal relay 206,

left-hand armature and contact of relay 20T,

winding of relay 202, left-hand armature and back contact otrolay 201 to ground at the left-hand armature and contact of relay 200. Relay 202becomes energized and completes a circuit in parallel to the one just traced extending through the winding of relay 203 to ground at the Contact and righthand armature of relay 202. Relay 203, however. does not energize at this time due to the fact that it is shunted by the direct circuit to ground at the left-hand armature Moreover, relay 206, which is also included in the circuit of relays 202 and 203, is not operated since it is marginal and does not receive sufficient current to attract its armatures. Relay 202 also completes a circuit from' battery through the winding of relay 201i, winding of relay 205 to ground at the contact and right-hand armature of relay 202. Relays 20e and 205 operate and a circuit is closed from subbattery through the right-hand armature and contact of relay 109, conductor 170, outer righthand armature and contact of relay 205,*winding of relay 201 to ground. Relay 201 actuates and locks all) up through its right-hand armature and front contact independently of the outer right-hand armature and contact of relay 205. Relay 201, on attracting its left-hand armature, opens the shunt circuit around relay 203, permitting this latter relay to energize inv series with relays 206 and 202. The Jfunction ot relay 203, which, it will be noted, is operated immediately following the insertion of the plugin the jack, is to connect the operators telephone set 210 to the strands of the cord circuit taken for use in answering the calling subscribers line. The operator may now converse with the calling subscriber to learn the number' of the line with which he wishes connection. Talking current is supplied to the calling line in a circuit from battery through the lower left-hand winding of repeating coil 117, winding of supervisory relay 115, conductor 140, front contact and inner lefthand armature of relay 203lower contacts of ringing keys 21st, 213, 212 and 211, outer right-hand armature'and contact ot relay 203, contact and right-hand armature of relay 200, conductor 105, tip of plug 104;, tip oit jaclr 103, over the loop of the calling line, ring of jack 103, ring of plug 1011, conductor 106, front contact and outer lefthand armature of relay 203, upper contacts of ringing keys 214, 213, 212 and 211, inner right-hand armature and frontl contact o1 relay 203, conductor 139, upper left-hand winding of repeating coil 117 to ground. Talking current is furnished to .the v operators telephone set from a local source as will be obvious from an inspection of the f drawing.

As soon as relay 202 operates a circuit is completed from battery through the winding of the power magnet of sequence switch 110, conductor 167, left-hand armature and tront contact of relay 202, conductor 106, lower contacts oit sequence switch spring 1111 to subhattery and ground. Sequence switch magnet 110 is energized in this circuit and advances the several sequence switch springs out of position 1 and into position 2. In position 2 a circuit is closed for the calling supervisory lamp` 131 which extends from subbatt-ery through the lower right-hand contact oi sequence spring 171, lamp 131, resistance 132 to ground. Lamp 131, however, remains eX- tinguished since it is shunted by means of a circuit from subbattery through the lower right-hand contact of sequence switch spring 171, upper right hand contact ot said springs, armature and contact of supervisory relay 115, which is operated due to the fact that the calling subscribers receiver is oil the switch hoolr, resistances 133 and 132 to ground. In position 13 of sequence switch110, when spring 171is open at its upper right contact, the shunt circuit of switch lamp 131 leads through the right contact of relay 112. in position 2 oit sequence switch 110 a. circuit is .closed from subbattery through lamp 125, resistances 123 and`122, upper right-hand contact of sequence switch spring 12T (2-1-11), lower lett-hand contact ot' said sequence switch spring (2st-Mito ground. The lamp 125 burns' steadily in this circuit which is maintained until after sequence switch 110 leaves position 11 ollowing the completion of the function of the register sender. YThe lighted condition ot lamp 125 serves as an indication to the operator that the apparatus is ready tor the attachment of a sender. The lampv will continue to'burn until the sender is later released. v

Association of the sender 'wit/z the opcmors cowl circuit. Y

Vsubbattery through its right-hand armature and front contact, lower right-hand contact of sequence switch spring 307 (1), winding of sequence switch magnet 310 to battery and ground. Sequence switch 310 moves from position 1 into position 2. As the sequence switch leaves position 11/2 the original circuit of relay 301 is opened at the upper right-hand contact of sequence switch spring 303 but relay 301 remains energized in position 2 in a circuit which extends through the upper lett-hand contact of sequence switch spring 308 (1l/THT), back contact and right-hand armature of relay 300 to subbattery and ground. In position 2 of sequence switch 310 a circuit is closed from..

battery through the winding of the updrive power magnet 336, lower le't-handand upper right-hand contacts ot sequence switch spring 310, front contact and right-hand armature of relay 301 to subbattery and ground. Power magnet 336 energizes in this circuit and presses the depending portion ot the'shaift 340 'against the updrive power roll, causing the brush shait or" the cord finder to move upwardly. VVvlhcnjthc brushes of the cord ndcr encounter the ter minals representing the cord circuit taken for use by the operator, a circuit is closed `from battery through the windineP or relay 300, upper le'ftehand contact ot sequence switch spring'309 (2), brushV 347, terminal right-hand tracts its armature and opens the circuit ot register 405, which thereupon stops in position 4. When register 406 kreaches position l a circuit is closed from subbattery through the armature and contact of relay 415, upper lettdrand contact of spring 427 t 1) winding of relay 411,7.lower right-hand contact of sequence switch spring 328, and thence to battery and ground. Relay 411 opens the circuit of' register 406 permitting this register to stop in position 1. When register ".7 arrives in position 4 a circuit is closed treni subbattery through the contact and'armature of relay 41T, lower righthaud Contact oit' spring 428 winding of relay 412, up-

per .left-hand contact of sequence switch` spring 328 (l), and thence to battery and ground. Relay 412 opens the circuit o register 407, which consequently sto-ps in position 4.j Similarly, when register 408 reaches position 3 a circuit isicompleted from subbattery through the armature and contact of' relay 418, lower right-hand contact of spring 429 (3), winding of relay 413, upper right-hand contactof sequence switch spring 328to battery and ground. Relay 413 Vopens the circuit of register 408 which comes to rest in position 3. The circuits abo-ve traced for the relays 409, 410, 411, 412 and 413 all extend through the winding of relay 303, and thence to battery by way of the upper left-hand contact oit sequence switch spring 322. Relay 303 consequently energizes and at its left-hand armature and Contact supplies battery current for itself and the relays 409, 410, 411, 412 and 413 by way of the upper contactl of sequence switch spring 333. |This substitute holding circuit is provided in order that relay 303 and the several stop relays 409, 410, etc. may be held energized after the cord finder i sequence switch 310 has lett position 6.

As soon as the first two registers, namely the class register 404 and the district brush register 405,1have been positioned, the cord inder sequence switch 310V is moved out of position 3 and intoposition 4. The circuit for advancing sequence switch 310 may be traced from battery through the winding o1 the magnet oitl said sequence switch, lower contact of sequence switch spring 306 contact and left-hand armaigselfio 10 is moved out o1' position 4 andV into po y sition 5 by ine-ans ot a circui t. from battery through the winding oi' niaL Aiet 310, lo wer left-hand contact of sequenccswitch spring 306 front contact and mature oitrelay 411, armature and contactpo relay 4l6 to subbattery and ground. lWhen the remaining two o'iice registers 407 and are po-V sitioned the cord hinder sequence swi' "1h 310 is advanced into position 6by nieanso the following circuit: battery, through the winding et magnet :310, lower right-hand, Contact or sequence switch spring 305 (5), contact and left-hand armature of reiay 412, front contact and VarmatureV of relay 413, armature and Contact of relay 419 to subbattery and ground. 1

At the time the operator sets up the nu merical record on t-.he lreys ef'rows 500, 501, 502 and 503, she also depresses the start hey which closes a circuit froin'subbattery through the lett-hand contacts of said key, con ductoi*533, winding of relay 515, conductor 534, conducto 441, and thence to battery as above traced at the leiitshand armature and contactVV of relay Relay 515 becomes energized and closes a locking circuit lior itsertl independently o start key 520. This locking circuit may be traced from subbattery'through the lower contactsV of sequence switch spring 311 (LI-6)', conducto-r 361, left-'hand armature and contact and winding of relay 315, and thence to battery,'as above described. Relay 515, at 'its right-hand armature and contact, coinpletes a circuit for relay 514. Relay W 014 closes a circuit from subbattery through its lett-hand armature and Contact, and thence Yover a plurality of parallel branches, one

of which leads through the right-aand armature and centact of relay 509, winding of the magnet 01"' register 504;V another' through the right-hand armature and contact ot' relai.7 510, winding of the magnet of register e055 another thrcugh the righthand armature and contact of relayV 511, winding ot the magnet et register 506; another through the r *1n-and armature and Contact ot win-:ling of the magnet of register t: and the last through the armature anc baci; centact ot relay 513, winding of the in guet ci i 508, which branches then lead re by way of conductors 539, and the contact-s of sequen switch springs 323 and closed .in position -2-6, to battery `and ground, The r 505, 506, T and 508 are enerifi/.ed iuthese circuits and commence to rotate in search orp the positions determined by the particular 4 'isters 504, Y

` switch spring 135.

Aspring 135 (8-f-6) to lower left-hand contact of sequence switch spring 128 (2), front Contact and left-hand armature of relay 120, back contact and right-hand armature of relay 113, lower right-hand contact of sequence switch spring (2-I-18) to subbattery and ground. Se-

quence switch moves from position 2 to position 3. in position 3 a circuit is clos-ed for the updrive power magnet 14?, traceable from hatten7 through the winding of said magnet, lower right-hand contact of sespring 128 (3), front contact quence switch and left-hand armature of relay 120, and thence to subbattery and ground at sequence 'lhemagnet 14? causes the upward movement of the brush shaft 150 to select the proper set of brushes to be used in extending the calling line. v

The stepping relay 600, which also energizes in the fundamental circuit, coinpletes a circuit from subbattery through its Contact and armature, conductor 628, upper contact. of sequence switchV spring 321 (S4-8), upper right-hand Contact of sequence switch spring 653 (2), Contact of spring 433 of the, class register, closed in position 2, lower right-hand contact of' spring 436 of the district brush'register 465, closed in position 4, conductor 442, armature and back contact of the No. 4 counting relay 631 winding of No. 4 counting relay 632 to battery. Relay 632 euergizes in this circuit and prepares a circuit from .battery through its winding, the winding of relay 631, contact and armature of relay `632, right-hand contact of sequence switch spring 620 (2) to subbattery. Relay 631, however, being shunted out by! the direct path to subbattery at the armature and contact of relay 600 does not become energized at this time. As Ysoon. as the brush shaft 150 of the district selector switch in its upward movement approaches the first brush tripping positio-n, commutator brush 158 engages the first metallic segment of commutator 161 and a circuit is closed as follows for relay in shunt of the step'- ping relay 600 in the fundamental circuit: battery, through the winding and contact and right-hand armature of relay 120, lower right-hand contact of sequence switch spring 144, upper right-hand Contact of sequence switch spring 142 (21/2-l-3) commutator 161, brush 158, upper contact of sequence switch subbattery. The stepping relay 600;r being shunted out, decuergizes and removes the shunt from around the winding of the No. 4 counting relay 631. Relay 631 thereupon energizes in se ries with relay 632. When brush 158 reaches the next insulating segment of coinmutator 161. the shunt is removed and the stepping relay 600 again energizes and a circuit is completed from subbatter f through its armature and contact, concluetor `628, and thence, as above traced, to the conductor 442, armature and front contact of relay 631, armature and back contactof the No. 3 counting relay 629, winding of relay 630 to battery and ground.' Y Relay 630 energizes and complet-es a series circuit for itself and relay 629, which latter relay, however, does not energize due to the fact it is shunted out. Uien the connnutator brush 158 engages the next metallic segment of the commutator 161, relay 600 Vis shunted, deencrgizes and removes the shunt. Afrom`l around the winding of relay 629, which relay thereupon Voperates in series with relay 630. ln like manne-r, for each brush tripping position to which the brush lshaft 150v is driven, a pair of counting relays are energized and locked up until finally the Oy and O counting relays 634 and 625, respectively are energized. Relay 625, at its outer armature and contact, opens the fundaniental circuit to prepare for the, release of relay 120. Relay 625 also completes a circuit from battery `through the winding of sequence switch magnet 610, contact and inner armature of relay tact of sequence subbattery and switch 610 out 625, left-hand conswit-ch spring 620 (2) Vto ground for driving sequence of position 2 and into position As sequence switch 610 leaves position l2 the contacts of spring- 620 are opened and the energized Lcounting relays are permitted to release.

As soon, following the opening of the fundamental circuit by the 0l counting relay, as the brush 158 engages the next insulating segment of commutator 161, the holding` circuit of relay 120 is opened and this relay retracts its armatures to open the circuit of the power magnet V147. The switch shaft 150, therefore, comes to rest in the position for tripping the proper set of brushes. Relay 120 completes a circuit from battery thro-ugh the winding of sequence switch magnet 110, lower right-hand contact of sequence switchl spring 130 (3), back contact and left-hand armature of relay 120 to subbattery and ground at sequence switch spring 135, driving sequence switch 110 out of position 3 and into position 4. In position 4 a circuit is completed from battery through the winding of trip magnet 146, upper left-hand contactof sequence switch spring 134 to subbattery and ground. The trip magnet 146 energizcs and rotates the trip spindle. 149 such that the selected set of brushes will be tripped on, the next movement of the shaft 150.

It will be recalled that the cord iinder sequence switch 310 is advanced from position 4 into position 5 only after the district group register 406 has reached its set position. lf, therefore, sequence switch 310 has reached position 5, indicating` that the district group register' has been setat the ifi) ^ into position 5.

time the sender sequence switch 610 reaches position 3,v said sender sequence switch is driven immediately into position 4 by means of the following circuit: battery, through thewinding of sequence switch magnet 610, lower left-hand contact of sequence switch spring 615 (2-l-18), upper left-hand contact of sequence switch spring 615 (3), lefthand contact of sequence switch spring 325 (5d-15) to subbattery and ground. lWith the sequence switch in position 4 and sequence switch 610 in position 4, the fundamental circuit is again closed, as above traced, for controlling group selection at the district switch. The relay 120, which energies in the fundamental circuit, locks up in the manner above described and also completes a circuit from battery through the winding of sequence switch magnet 110, lower left-hand contact of sequence switch spring 123 (4), front contact and left-hand armature of relay to subbattery and ground at sequence switch spring 135. Sequence switch 110 moves from position 4 1n this position the circuit of the power magnet 14'? is again closed, as above traced, and the brush shaft 150 is moved upwardly to advance the tripped set of brushes 151, 152 and 153 over the terminals vof the contact bank to select the proper group thereof. The stepping relay 600, which also operates in the fundamental circuit, completes a circuit from subbattery through its contact and armature conductor 628, upper contact of sequence switch spring 321 (v3-t8), lower rightfhand contact of sequence switch spring 623 v(4), contact of spring 434 (1-1-3), upper right-hand contact of spring 438 (1) of the district group register 406, conductor 445, armaturey and bach contact of counting relay 635, winding of relay 636 to battery. Relay 636 operates and closes a series circuit for itself and relay 635. Relay 635, however', remains deenergized since its winding is shunted outV by the stepping relay 600.

lWhen the brush shaft 150 approaches the first group selecting position, commutator brush 159 encounters they first metallic seg-k ment of commutator 162 and the following circuit is closedy for relay 120 in shunt of the stepping relay 600 in the fundamental circuit: battery, through the winding and contact and. right-hand armature of relay 120, lower right-hand contact of sequence switch spring 144 (2-1-5), upper left-handcontact of sequencel switch spring V142 (4l/2-f-5), commutator 162, brush 159 to sub battery through the upper contact of sequence switch spring 135. mains energized butthe-stepping relay 600, being shunted, 'releases its armature and opens the shunt" circuit around the No. 1 counting relay 635. Relay operates in series with relay 636, the circuit Relay 120 rethrough the winding of said magnet, lower 635 thereupon armature and contact of the 0l counting relay to terminate the movement of the switch. rl`he 0 counting relay 625, at .its inner armature and contact, completes the circuit above traced for driving the sender sequence switch out of 'position 4 and into v position 5. On leaving position 4 the sender sequence switch opens its contact 620 to allo-w ther energized counting relays to release.

As soon, after the fundamental circuit is opened at the sender, as the brush 159 engages the next insulating segment of coinmutator 162, relay 120 becomes deenergized and, opening the circuit of the power magnet 147, causes the brush shaft 150 to come to rest in operative relation with the proper group of trunks. Relay 120, furthermore, completesy a circuit from battery through the winding of sequence switch magnet'110, lower right-hand contact of sequence switch spring (5), back contact and leftshand armature of relay 12() to subbattery at sequence switch spring 135. Sequence switch 110 is advanced from position 5 into position 6.

In position `6 of the district sequence switch 110 a circuit is closed from battery through the right-haiid winding of test relay 114, vlower left-hand 'Contact of sequence switch spring 143 (6-1-7), lower right-hand Contact of said spring (2%1-6) to subbattery and ground'. Relay 114 energizes in this circuit. and closes the following locking circuit for itself, provided the first trunk in the group, upon the terminals of which the brushes 151, 152 and 153 are -now standing, is busy: battery, through the left-hand winding and front Contact and 'left-hand armature of relay114, test brush 153 to subbattery connected to the test terminal of the busy trunk. Relayl 114 completes a circuit from battery throughthe winding of sequence switch magnet 110,.lower left-hand contact of sequence switch spring 128 (6), front contact-and right-hand armature of relay 14, back Contact and right-hand armature of relay 113, lower right-hand contact of sequence switch yspring (2a-18) to subbattery. Sequence switch llOinoves out of position 6 and into position 7. In position 7 a circuit is again closed for the updrive power magnet 147, traceable from battery right-hand contact of sequence switch spring 128`(7), front contact and right-hand armature of relay 114 to subbattery at sequence switch spring 135.

The' brushes 151, 152

otspring 123 (i7), the right-hand armatureVY f and front contact of relay 114. to subbattery at' the lower'contact of .sequencewswitch spring 135. The brushes being accurately centered the above traced circuit is opened and relay 114 releases to open the circuit ot the lupdrive power `4magnet 147. Relay 114, inv addition7 completes aeircuit trombattery through the windingofl sequence switch magnet' 110, lowerviight-hand Contact of sequence Vswitch spring 139,':bacle AContact and-.right-hand armature ot-'relay 114t0 subbattery at the sequence switch spring 135, driving sequence switch 110 out Vot position 7 fandyinto-.position `3. llt willibefrecalled that the cord iindery senence switch `310= does .not pass into position (nntilthe oiiice andfbrush group lregistersftOZ 4and 403 havebeen positioned. Assuming these registers have been set at the time the distrietsequence switch 110 reaches position 3, a circuit is completed -as follows for lmoving the sender sequence switch G10 out-.oic position andzinto position' zibattery, through vthe winding of sequence switcli.mag-: net 610, upper right-.hand Contact of se--y quence switch spring 605 upper lefthand oontact'ot sequence switch spring 314 (6H-3), ybrush 344, terminalBO, conductor 3,53, lower lettehandf contact ot sequence switch =springi 134 (f3).- to siibbatterywand ground. When the sender lsequence rswitch advances toy Vposition 6 a circuit-is closed@ troni battery through the winding ot relay' 120.y lowenilett-hand `contacty o't sequence switcli1spriiigi1'42 (8)1, lower-lett-hand contaetiot sequencei switch spring 144 (S),` conductorf'f, terminal-349, brush 343, letthand contact ot sequence switch spring 315 (5i-t3), upper left-hand :contact of-sequenre switch: spring .317iy (Sel-11) ,lower righ'tehaiid contaotfot said 'spring (G4-8) to sub'battery and ground. ARelay "120 is energized and closes a :circuitlfroin battery through the winding .t sequence switch magnet 110, lower left-,hand Contact of sequence switch spring" 123 4(3),"Erfurt"contact and lett-hand armature 'of relay120 toHsubbattery at sequence-*switchspring 135. Sequence'switch` llladvaiices troni-positi-on 3 into position 9.' vlNhile the sequenee'switch 110 is passing` through position 3 inte position 9, relay y12() is held energized, first by means of a circuittrom battery through the winding and contact and right-hand armature otsaid relay, lower right-hand contact `ot sequence switch spring 137 ,(8-1-31/2), upper lett-hand con-J tact ot said'spring (2--i-ll/2), back contact and'deft-handaarmature of relay 113 to subbattery. As sequence switch 110 reaches position 3%, the following circuit is clo ed prior to the opening ot the circuit last traced and serves to hold the relay 12() energized atter the sequenceswitch moves into position 9 i battery, through the winding and contactand right-hand armature of relay 120, upper right-hand contactotl sequence switch spring 145 (S3/49), upper lett-hand contact ot said spring (3.|.11),.conductor 355, terminal 349, brush 343, left-.hand contact of sequence switchv spring 315 (BJI-3), .upper lett-hand Contact et sequencesw'itch spring 617 (ti-1411),y lower right-hand contact'ot said spring (G+S) to subbattery and ground. rThe relay 120 is maintained energized in this circuit: until oiiiice selection has -been completedv and the send-er sequence switch 61C). advances. out Vot position 8. It may be noted that springs 137 and 145 are out so as tozhave overlapping closures between positions 8 and 9. Accordingly, the lower-right Contact ot spring 137 does not open 4in point of time until slightly after-the upper right Contact of spring 145icloses.

Cpemtz'on. of oyj'ce selector. switch.

The fundamental circuitk is now extended" from the sender through to theoftice selector switch =in Fig.V 7 ready for controlling the ofi-ice brush selection. This circuit may be traced from battery through the right-hand windingfoit relay 700, `lower lett-hand contact oit sequence switch sprinff27'11 (1), lower righthand Contact of said spring (Ll-4), terminal 154, brushy y151, upper'right-hand contact/ot sequence'switcli spring 144 lower right-hand Contact ot sequencel switch spring 142 (9-1-11), conductor 354.,.terminal 348, brush letttfhandy contact ot sequence switch spi-ing 611y (6), Contact and outer armature :otrelay 625., kwinding ot stepping relai.T 3005 outer lett-h and armature and bach Contact vof relay' 601, lower'contact Otsequenee switch spring 606 (6), resistances 637 Land 627:, upperleft-:hand contact otV sequence switch spring V313 (3-|-8).=to subbatteryv and ground. `Relay'700 becomes energized and' completes a locking circuit for iteeltV traceable from battery through its right hand winding and front contact and inner right-handarmature, lower right-hand contact ot sequence switch spring' 716 (1e-10,), 1 lower right-'hand contact of sequenceswitch as described. Relay 700 also completes a circuit from subbattery through its lefthandv armature and front contactyupperlettspring 711 V(1-1-4), and thence to subbatteryl hand contact of sequence switch spring 707 (1), winding of relay 701 to battery. Relay 701 operates and locks up in a circuit through its front Contact and left-hand armature, test terminal 156, brush 153, letthand armature and back Contact of relay 114, upper right-hand contact of sequence switch spring 137 (61/2-I-161/2), upper lefthand contact of sequence switch spring 137 (2-{-161/2) to subbattery at the left-hand armature and back cont-act of relay 113. This circuit from subbattery to the test terminal 156 also serves to render the selected trunk busy to other district selector switches. Relay 701 operates and completes a circuit from subbattery through its right-handarmature and front Contact, lower lett-'hand contact 748 (1), winding of sequence switch magnet 710 to battery for driving saidvsequence sw'itch out of position 1 and into position 2.' In position 2 a circuit is closed from battery through the winding of the updrive power magnet 718, lower right-hand contact of sequence switch spring 707 (2),

f front-contact and left-hand armature of relay 700 to subbattery. Magnet 718 causes the brush shaft 720 to move upwardly for the purpose ot' selecting the proper set of brushes.

The stepping relay 600, which also energizes in the funda-mental circuit, completes a circuit from subbattery through its contact and armature, conductor 628, upper contact or" sequence switch spring 321 (3-1-8), upper lett-hand contact of sequence switch spring 623 (6), upper contact of spring 432 (1-1-3), lower right-hand contact of spring 439 (4), conductor 442, armature and back contact of relay 631, winding of relay 632 to battery. Relay 632 operates and prepares a series circuit for itself and relay 631, as here'inbei''ore explained. Relay 631 remains shunted out until the stepping relay 600 releases.

When the brushshaft 720 approaches its first tripping position, commutator brush 742 encounters a metallic segment of commutator 745 and a holding circuit is closed for relay 700 in shunt of the stepping relay 600 in the fundamental circuit. This holding circuit may be traced from battery through the right-hand winding and front contact and inner right-hand armature ot' relay 7 00, lower right-bami contact of sequence switch spring 716 (14,40), upper lett-hand contact oi sequence switch spring 711 (A-lf2), commutator 745. brush 7 42, left-hand contact of sequence switch spring 702 (124-5) to sub'- battery and ground. The stepping relay 600, being shunted out, releases and removes the short circuit from around the winding ot relay 631, permitting this relay to operate and lock up in serieswith relay 632. W hen commutator brush 742 encounters the next insulating segment, the steppingrelay 600 reenereizes and completes the circuit above traced to conductor 442, armature and fro-nt contact of relay 631, armature and back contact of relay 629, winding of the next counting relay 630 to battery. In a similar man-V ner to that already described, the relay 630 operates and prepares a series circuit for itselt and relay 629. This method of operation proceeds, a pair of counting relays being' energized and locked up for each tripping position passed over by the brush shaft 720, until the 0 and 0 counting relays are energized. The 0l counting relay 625, on operating, opens the fundamental circuit at its outer armature, and at its inner armature completes a circuit from battery through the winding of sequence switch magnet 610, contact and inner armature of said relay, lefthand contact of sequence switch spring 620 (6) to subbattery and ground. Sequence switch magnet 610 advances from position 6 into position 8. On leaving position 6 .the contact of sequence switch spring 620 is opened to cause the releaseol the energized counting relays.

As soon following the opening oi the fundamental circuit by the 0 "counting relay as the commutator brush 742 engages the next insulating segment of commutator 745, the holding circuit of relay 700 is opened and this relay releases its armatures to sever the circuit of the power maenet 718. the brush sh aft 720 thereupon comes to rest in the required position for tripping the proper set oi brushes 721, 722 and 23. Relay 700 at the saine time closes a circuit from. subbattery through its left-hand armature and back contact, upper left-hand Contact ot sequencev switch spring 748 (2), winding sequence switch magnet 710 to battery, moving said: sequence switch out of position 2 and into position 3.

)Vith sequence switch 710 in position 3 and the sender sequence switch 610 in position 8, the fundamental circuit, hereinbetore traced. is established preparatory to controlling the group selecting n'ioveinent of the oiiice selector. Relay 7 00, on energizing` in the fundamental cir-cuit, closes a circuit from subibattery through its lett-hand armature and iti-ont Contact, lower lett-handcontact of sequence switcl. spring 709 winding ot sequence switch magnet 710 to battery, driving sequence switch 710 out of' position 3 and into position 4. In position 4 the relay 700 remains locked up in the fundamental circuit in the manner above eX- plained. The circuit ot the updrive power magnet 718 is now completed through the lower .right-hand contact of sequence switch spring 707 (4), and the shaft is driven upwardly in the group selecting movement.

The stepping relay 600, which also energizes in Athe fundamental circuit completes a circuit from subibattery through its contact the sequence switch 710 in position 8: battery, through the left-hand winding of marginal relay 603, winding of sensitive relay 602, cuter armature and contact of relay 60-l,

lower left-hand contact of sequence switch quence switch spring 145 (114-16), hrush 152, terminal 155, lower left-hand Contact of sequence switch spring 714 (8a-0), resistance 715 to suhhattery andground. itelay 602 operates in this circuit butrelay 603,

being marginal, does not receive sufficient current in series with resistance 715 to attract its armatures. Relay 602, on operating, closes a circuit from subb-attery through its left-hand armature and front contact, lower left-hand contact of sequence switch spring 612 (9), winding of sequence switch magnet 610 to battery 'or driving sequence switch 610 out of position 9 and into position 10. Simultaneously with the closure of this circuit relay 602 also completes the 'lollowing circuit which is maintained from position 9 to position 9% of sequence switch 610, for causing the advance of the otlice sequence switch 710: battery, through the right-hand winding of relay 700, lower lefthand contact of sequence switch spring 711 (8), lower right-hand contact of said spring (S-l-Q), terminal 154-, brush 1.51,` upper right-hand contact of sequence switch spring 144 (lla-16), lower right-'hand Contact Voi sequence switch spring 142 (SH-11), concluetor 354, terminal 343, brush 342, lower righthand contact of sequence switch spring 611 (SH-9%), right-hand armature and contact oit relay 602, resistances 637 and 627, upper lett-hand contact of sequence switch spring 313 (3-}-3) to suhoattery. Relay 7 00 becomes energized and closes a circuit from battery through the winding of sequence switch 710, lower left-hand contact of sequence switch spring 709 (3), front contactl and lett-hand.armature ot relay'700 to subbattery, driving sequence switch 710 outoi position 8 and into position 9. lNhen, an 1nstant later, the sequence switch 610 leaves position 9%, relay 7 00 becomes deenergized and closes a circuit `from battery through the winding of sequence switch magnet 10, upper lett-hand contact of sequence switch spring 743 (9), and back contact and lefthand arm ature of relay 700 to suhbattery for moving sequence switch 710 out of position 9 and into position 10. As sequence switch 710 leaves position 9 the above traced circuit for the sensitive relay 602 is opened at the lower left-hand Contact of sequence .switch spring 714. Relay 602, on releasing` its armatures, closes a circuit from battery through the winding of sequence switch magnet 610, lower left-hand contact of sequence switch spring 605, bach contact and lefthandarmature of relay 602 to subbattery, driving sequence switch 610 into position 11.

The district and oilice selector switches have been positioned and the sender is now in condition to control the selective movements of the incoming and linal switches, provided the operator has completed the setting up of the numerical record on her keyboardr at this time. lt is not thought necessary to show the circuits in detail for the incoming and inal switches, inasmuch as they have no direct bearing on the subject matter of the invention claimed. Accordingly, theseswitches have heen diagrarnmatically illustrated as shown in Fig. 7. Provided the numerical lreys have all been depressed, the circuit, hereinbefore traced, which leads through the contacts and armatures of relays 509, 510, 511, etc. has heen` closed to advance the cord. finder sequence switch out of position 6 and into position 7, from whence it is driven into position 8 following therelease of the operators keys, as already explained. )Vith sequence switch 310 in position 3 the sender sequence switch is immediately driven out of position 11 and into position 12 by means of a circuit from battery through the winding of lsaid sequence switch, upper left-handy contact of sequence switch spring 612 (11), left-hand contacts of sequence switch spring 317 (8), conductor 362, thence to conductor 362, Fig. Il, lower left-hand contact of spring 431 (2) to subbattery.

For clearness, the conductor 362, which leads, as mentioned, from the sequence switch spring k317 in Fig. 3 to spring 431 in Fig. Li, has been omitted and the convention ot' the circles containing corresponding Ronan numerals adopted in its stead. This same convention is also used, as will appear hereinafter, in substitution of certain ther conductors which have beenv omitted troni the drawing to avoid unnecessary confusion. rifhe spring 431 in Fig. e is a part Vsaid spring (1l-#16), conductor 633, and

lli.)

thence to conductor 633, Fig. 4i, upper lefthand contact of spring e30 (2) to subbattery and ground. i hatteryythrough the winding it ltelay 625 completes a circuit 

